Ratchet and pawl mechanism for hand brakes



Feb. 22, 1949. s HASEL-HNE I 2,462,183

RATCHET AND PAWL MECHANISM FOR HAND BRAKES Filed Max 011 23,1946 2 Sheets-Sheet 1 I72 Ven Zor 193;! B. Eas l/fine.

Feb. 22, 1949. -s. BJHASELTINE RATCHET AND PAWL MECHANISM FOR HAND BRAKES 2 Sheets-Sheet 2 Filed March 23, 1946 Patented Feb. 22, 1949 RA'ECHET AND PAWL MECHANISM FOR HAND BRAKES Stacy B. Haseltine, La Grange, Ill., assignor to W. H. Miner, Inc., Chicago, 111., a corporation of Delaware Application March 23, 1946, Serial No. 656,594

8 Claims.

and efficient means for throwing the dogs into and out of engagement with the ratchet wheels.

A more specific object of the invention is to provide a mechanism as set forth in the preceding para raph, wherein the locking dogs are connected to each other by a rocker, and the means for throwing the dogs into and out of en agement isin the form of a lever operated, rotary trip element having radial arms engageable with the rocker to lift and depress the same and the dogs therewith to bring the latter into and out of operative. engagement with the ratchet wheels.

Other objects of the invention will more clearly appear from the description and claims hereinafter following.

In the drawings forming a part of this specification, Figure l is a transverse, vertical sectional view of the upper portion of a hand brake mechof the power multiplying, gear driven type, corresponding substantially to the line l-l of Figure 2, illustrating my improvements in connection therewith. Figures 2 and 3 are vertical sectiQnal views, corresponding respectively to the lines,2-2. and 3-3. of Figure 1. Figure 4 is a vertical sectional view, on an enlarged scale, through the locking dogs, in a plane parallel to the plane of the view in Figure 3, looking from right to left in Figure 1, showing, the rocker in elevation and the trip element in position to lift the rocker. Figure 5 is a view, similar to Figure l, on. an enlarged scale, showing in full lines the positions of the parts when the dogs have been completely disengaged from the ratchet wheels by the trip element, and illustratin in dotted lines the position of the trip element and its lever at the beginning of the disengaging operation. Figure 6 is a horizontal sectional view, corresponding substantially, to the line 6-45 of Figure 1, showing the brake housing only.

The drawings illustrate my improvements as embodied in a well-known type of power multiplying, gear driven lorake, employing the usual chain windin drum, not shown, which is rotated by adriving pinionw l0. actuated by the hand wheel of the brakes, not shown, and meshingwith a gear H, which is rotatable with the drum. The parts of the brake mechanism are contained in the usual housing I2, the upper portion only of which E shown in the drawings.

My improved hand brake mechanism comprises broadly a pair of ratchet wheels A-A rotatable with the driving pinion which actuates the winding drum of the brake mechanism; a set of two lockin dogs B and C; a rocker D connecting the dogs B and C; an actuating lever E; and a rotary trip element F operated by the lever.

The ratchet wheels A-A are preferably formed integral with the shaft [3 which carries the pinion it, which is also formed as an integral part of the shaft. The shaft 13 is actuated by the usual hand wheel which is located on the shaft exteriorly of the housing l2. The opposite end portions of the shaft it are journaled in bearings provided in the front and rear walls It and 15 0f the housing. As shown most clearly in Figures 2 and 3, the rear wall l5 of the housing is in the form of detachable closin plate.

Each ratchet wheel A is in the form of an annular flange projecting from the shaft l3 and having peripheral ratchet teeth It thereon. The teeth of the two ratchet wheels are arranged in staggered relation, that is, the teeth of the two wheels alternate with respect to each other, the teeth of one wheel being advanced the distance of a half tooth with respect to the teeth of the other wheel. Although the rotary ratchet means has been described as composed of two laterally spaced ratchet wheels, it will be evident that'the same may also be. properly regarded as a single ratchet wheel having two sets of ratchet teeth which are laterally separated by a groove.

Above the pinion It, the rear wall iii of the housing is inwardly offset, as shown, the vertical wall section of said offset portion-being indicated by I].

The operating lever E, which is arranged exteriorly of the housing at the forward side thereof, is provided with a laterally projecting, cylindrioal boss 18 which forms a pivot member'at its lower end, journaled in a bearing opening l9 in the front wall it of the housing, The boss l8 has a central bore 20 which also extends through the lever and is adapted to accommodate a retaining bolt 21 which holds the operating lever E against removal, as hereinafter pointed out.

The trip element F comprises a relativelyheavy, tubular'sleeve or collar portion having a pair of oppositely disposed, radially projected arms 22 and 23. extending therefrom. The armsv 2-2 and 23 preferably have hook-shaped ends-,as show-n.

3 These arms 22 and 23 extend from the tubular sleeve portion at a point approximately midway between the ends thereof and are connected by a rounded web or flange portion 24 on said sleeve projecting therefrom, and extending around the lower side thereof, as seen in Figure 1. At its inner end, the sleeve portion is reduced in diameter to provide a bearing section 2-5 by which the sleeve is rotatably supported in a bearing opening 26 in the wall l1 in alignment with the bearing opening [9 of the front wall. The forward end of the tubular portion of the element F bears on the inner end of the boss l8 of the lever E, the boss being provided with a projecting locking key portion I24 engaged in a key seat I in the element F. The element F is secured to the lever by the bolt 2| which extends through the element F and the bore of the lever and boss, having its head bearing on the outer side of the lever, and the nut 27 thereof engaged with a washer 28 bearing on the inner end of the trip element F. In addition to securing the parts together, the bolt 2| prevents removal of the lever by the washer 28 overlapping the wall I! at the bearing opening 26.

The dogs B and C are of similar design, each dog being in the form of an elongated, rectangular block having a tooth 29 at its lower end. These two dogs are arranged side by side in spaced relation, on opposite sides of the flange 24 of the trip element F between the walls l4 and I! of the housing and in alignment with the ratchet wheels AA respectively. At the forward side edges, the dogs B and C slide on the inner side of the left hand side wall 30 of the housing, as

seen in Figure l, and are guided along their rear side edges by engagement at their upper ends with the curved periphery of the sleeve portion of the element F and at their lower ends by vertical guide flanges 3|-3l which project laterally from the walls i4 and I! respectively and are in transverse alignment with each other. The two dogs are thus restricted to sliding movement in vertical direction. Upward movement of the dogs is limited by a transverse stop wall 32 which is slotted, as indicated at 33, to permit the arm 22 of the trip element to pass. The wall 32 is in the form of a horizontal flange projecting from the front wall [4 and the side wall 30 of the housing,

being located at the corner formed by these walls.

The wall 32 preferably extends to the rear wall I! of said housing.

The rocker D is in the form of a relatively short, cylindrical pin which connects the dogs. The

pinlike rocker D extends transversely of the dogs,

having its opposite ends engaged in openings 34-34 adjacent the upper ends of said dogs. The opening 34 of each dog is outwardly flared at opposite ends, the flared portions extending from the center of the dog to the outer sides thereof, thus providing a bearing which permits swiveling of the corresponding end of the pinlike rocker engaged therein.

As will be seen, the rocker D is in the path of rotary movement of the arms 22 and 23 of the trip element, these arms being respectively en gageable with said rocker at a point midway between ,the ends thereof to depress and raise the latter as the trip element is rotated in reverse directions, and thereby engage the dogs with and disengage the same from the ratchet wheels. The flange 24 of the trip element F engages between the dogs B and C at all times, thus maintaining the dogs laterally spaced and in proper alignment with the ratchet wheels.

The operation of my improved brake mechanism is as follows: In applying the brakes, the ratchet wheels A A are rotated in clockwise direction, as seen in Figure 1, the dogs B and C ratcheting over the teeth of the same, being yieldingly held in engagement with the teeth of the respective wheels by the action of gravity on said dogs and the added weight of the lever E, which, acting through the arm 22 of the trip element F, presses downwardly on the rocker D, the

force being transmitted to the dogs through the rocker. As will be evident, alternate engagement of the dogs B and C with the ratchet means provided by the two wheels AA, is provided by the rocking action of the rocker D.

Inasmuch as the teeth of the two ratchet wheels are staggered with respect to each other and each wheel has a locking dog cooperating therewith, relatively fine locking adjustment of the brakes is had, the ratchet mechanism being locked against backward rotation, that is, rotation in brake releasing direction, at half tooth intervals.

To release the brakes, the lever E is swung to the right until the arm 23 of the trip element F is engaged underneath the rocker D, as shown in Figure 5. This position of the lever and the trip element corresponds substantially to the dotted line position thereof, indicated by 35 in Figure 5. Upon releasing the pressure on the particular tooth which is in full locking engagement with one of the teeth of the corresponding i ratchet wheel, by slightly tightening the brakes, that is, rotation of the ratchet wheels in clockwise direction, the weight of the lever E, in its overbalanced condition, lifts the rocker D and the dogs B and C, thus automatically disengaging the latter from the ratchet wheels, as shown in Figure 5. The position of the lever E, when the dogs have been fully disengaged, is shown by the dotted lines 36 m Figure 5. Inasmuch as movement of each dog 38 and C, away from the ratchet wheel, is limited by the stop wall 32. complete withdrawal of both dogs to disengaged position is assured, even if one dog has been arrested before the other, the lever action of the rocker acting between the dogs bringing the other dog to fully Withdrawn position in engagement with the stop wall 32.

The dogs B and C may also be forcibly disengaged from the ratchet wheels by manually swinging the lever E. to the final position indicated by 36 in Figurefi, without slight tightening of the brakes.

To reengage the dogs with the ratchet wheels, the lever E is swung from the position 36 in Figure 5 to the left and to the position shown in Figure 1, thereby engaging the arm 22 of the trip element with the rocker D, forcing the same downwardly and bringing the dogs in engagement with the ratchet wheels.

I claim:

1. In a hand brake mechanism, the combination with a member adapted to be rotated to tighten thebrakes; of a ratchet element rotatable with said member, said element having two laterally spaced sets of inclined peripheral teeth, the teeth of said two sets being staggered with respect to each other; a pair of locking dogs respectively engaged with said sets of teeth; a rocker connecting said dogs; and a leveroperated trip member engageable with said rocker to move the same and the dogs therewith into and out of engagement with said ratchet element.

In a hand brake mechanism, the combination with a member adapted to be rotated to tighten the brakes; of a pair of ratchet wheels rotatable with said member, said wheels having inclined ratchet teeth; a locking dog engageable with the teeth of each ratchet wheel; a rocker connecting said locking dogs; and a lever operated trip element having spaced shoulders respectively engageable with said rocker to move the dogs into and out of engagement with the ratchet wheels.

3. In a hand brake mechanism, the combination with a member adapted to be rotated to tighten the brakes; of a pair of inclined ratchet wheels having ratchet teeth, the teeth of said wheels being staggered with respect to each other; a pair of sliding dogs respectively engageable with said ratchet wheels; a rocker extending between said dogs and connecting the same; and lever operated means engaging said rocker between the ends thereof to depress and lift the same and throw said dogs into and out of engagement with the ratchet Wheels.

4. 'In a hand brake mechanism, the combination with a member adapted to be rotated to tighten the brakes; of a pair of ratchet wheels rotatable with said member, said ratchet wheels having teeth arranged in staggered relation; a pair of sliding dogs respectively engageable with said ratchet wheels; a rocker connected at opposite ends to said dogs; a pivoted lever; rotary means actuated by swinging pivotal movement of said lever in reverse directions, said rotary means having shouldered engagement with said rocker between the ends of the latter to depress and lift the same and the connected dogs to engage the latter with and disengage the same from said ratchet wheels.

5. In a hand brake mechanism, the combination with a member adapted to be rotated to tighten the brakes; of a pair of ratchet wheels rotatable with said member, said wheels having teeth arranged in staggered relation with respect to each other; a pair of sliding locking dogs respectively engageable with said ratchet wheels; a rocking pin connected at opposite 'ends to said dogs; a rotary trip element; and a lever for rotating said element in reverse directions, said trip element having circumferentially spaced, radial arms respectively engageable with said rocking pin intermediate its ends, for moving said pin and connected dogs toward and away from the ratchet wheels.

6. In a hand brake mechanism, the combination with a member adapted to be rotated to tighten the brakes; of a pair of ratchet wheels rotatable with said member, said wheels having ratchet teeth thereon, the teeth of one wheel being staggered with respect to the teeth of the other wheel; a pair of sliding locking dogs respectively engageable with said ratchet wheels; a

connecting pin extending between said dogs and having its opposite ends swiveled to said dogs respectively; and a rotary trip element having circumferentially spaced, radial arms respectively engageable with said pin at a point intermediate its ends to depress and lift said pin and the connected dogs therewith upon rotation of said trip element in reverse directions, to engage said dogs with and disengage the same from said ratchet wheels.

7. In a hand brake mechanism, the combination with a member adapted to be rotated to tighten the brakes; of a pair of coaxial, laterally spaced ratchet wheels rotatable with said member, said wheels having ratchet teeth, the teeth of each of said wheels being staggered with respect to the teeth of the other wheel; a pair of laterally spaced, sliding locking dogs respectively engageable with said ratchet wheels; a pin extending between said dogs and having swiveled connection at opposite ends with said dogs respectively; and a lever actuated trip element rotatable in reverse directions, having radially, oppositely extending arms which are respectively engageable with said pin intermediate its ends to depress and lift the same and the dogs therewith to engage the latter with the ratchet wheels and disengage the same therefrom.

8. In a hand brake mechanism, the combination with a member adapted to be rotated to tighten the brakes; of a pair of laterally spaced ratchet wheels rotatable with said member, said wheels having ratchet teeth, the teeth of each wheel being staggered with respect to the teeth of the other wheel; a pair of sliding locking dogs respectively engageable with said ratchet wheels, said dogs being laterally spaced; a lever actuated trip element rotatable in reverse directions, said element being supported to one side of said dogs and having radially extending, oppositely projecting arms swingable in the space between said dogs; and a rockin pin extending between said dogs and having its opposite ends connected thereto, said pin being in the path of swinging movement of said arms and engageable thereby to be respectively depressed and lifted to move said dogs toward and away from said ratchet Wheels.

STACY B. HASELTINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,125,325 Hood Jan. 19, 1915 1,510,333 O'Connor Sept. 30, 1924 2,179,674 Stolpe Nov. 14, 1939 

